@Chah It's already been explained. Their family causes a dispute in the kingdom and essentially ruins it. By destroying the family and its influence, she's trying to save everyone else.
Source: I speedread the whole thing. Try chapter 7.
@Chah like what @Cynic said, it's already been explained. She's trying to save everyone in her family by making the influence drop for a while. This is because if the influence gets too big, as mentioned in the chapter, bigger than the royal family, people who want them to fall will start to hunt them down. This would most likely result in a bigger consequence than bringing herself to ruin, because if only she is ruined, then all of the eyes will be pointed at her instead of her family.
I actually like the romance in this. Too many good stories in this genre are ruined by god awful MLs, but Addie is so sweet, and they're perfectly suited for each other.